Various control methods are already known for the treatment of bulk goods. These include measuring and determining the values relating to the condition of the goods before the treatment phase. The values are then compared with predetermined theoretical values for the purpose of influencing the goods during the treatment phase by variable treatment measures governed by the measurement data. Drying processes frequently occur in the course of manufacturing or treating vegetable bulk goods such as grain, beet slices, tobacco or pharmaceutical bulk goods. This type of material is more or less moist at the outset and a predetermined degree of moistness is required to be maintained in the finished end product.
Difficulties are incurred when the known control systems for drying the material are required to maintain the predetermined moisture content within narrow tolerance limits. This is especially true when the known control systems are used in continuous production plants having a relatively high output demand. Frequently, there are delays in maintaining the quantity constant and occasionally faulty batches of the end product result. That is, there is a time-lag involved in effecting the modifications in the technology, i.e., the characteristic physical properties of the material are greater than the time available for influencing the material during the continuous working. The effectiveness of the known control devices occurs belatedly so that occasionally, inferior material below established quality standards is obtained. There is only a short period of treatment time available during the processing of the material. This material is unable to benefit from the action of measures resulting from the data obtained. Consequently, there is a time lag before the particular action controlling the drying process becomes completely effective. Because the properties of the raw material fluctuate considerably, wide fluctuations occur in the technological properties of the end product.